1. Field of the Invention
The invention generally relates to an integrated head up displaying (HUD) device including a housing that houses an active-matrix image projecting system and its accompanying electronics, and an optical combiner (for providing a see-through image thereon) connected to the housing via a retractable arm attached at one end to the main body and holds the HUD optical panel at its other end. In particular, the telescopically retractable arm allows the assembly to extend or retract for a desirable combiner height. Further, the LED backlighting array is placed within a reflective light chamber which is lined with a safe, light-weight, low cost, specular, reflective sheet for high reflectivity. The non-conductive, reflective sheet also covers the LED printed circuit board.
2. Description of the Related Art
Head-up display (HUD) devices are widely used in vehicles for both business and home purposes. The use of and developments in HUD technology continue to explode. Current HUD systems differ from one another in terms of projection technology, resolution, positioning-adjustability, viewing flexibility, size, shape, and installation convenience. For example, U.S. Pat. Nos. 3,503,146 and 5,841,408 teach an automatic apparatus for moving a combiner assembly away from the pilot's head only in the event of a crash. U.S. Pat. No. 3,945,716 rotates the HUD about an axis in line with the pilot's head. It is slaved to a Forward-Looking-Infra-Red (FLIR) or TV tracker and the entire unit (including the combiner) turns with the pilot's head. The system uses a CRT for the display and an expensive holographic lens. It has only one pivot point to move the combiner.
U.S. Pat. No. 5,381,267 uses a four bar linkage to support a HUD combiner to swing between an upper storage position and a lower operating position solely to stow the combiner assembly. It is not possible to adjust the display (arranged at an identical desired viewing angle) to different vertical positions.
U.S. Pat. No. 4,188,090 provides a complex HUD combiner and optical projector, combined as a solid single unit for one eye, i.e., a monocular system. The unit is hinged and rotates to a stowed position. However, the monocular system is designed so the viewer's eyes are always approximate to the focal point of the objective lens thereby maintaining an image subtended size and a viewing angle, rather than providing viewing flexibility. In addition, the flat combiner does not support any focal change.
U.S. Pat. No. 4,937,665 shows a small mirror adhered to the inside of a car windshield and above the driver's line of sight, for reflecting back a video, movie, TV program, etc. to one eye of the driver. A display is separately mounted overhead and is focused to infinity.
U.S. Pat. No. 6,078,428 mounts a head-up collimator (including a projector and a semi-transparent mirror that is used by being placed before the user's eye) in a support. By adjusting bolts and hinges of the support with the feature of potting a tapered pin in resin, exact alignment of the support with respect to the structure of the aircraft in axes X, Y and Z during reinstallation after maintenance becomes possible. However, the semi-transparent mirror is only allowed to rotate about the x-axis, but cannot be vertically lifted with respect to the projector without rotation.
U.S. Pat. No. 6,445,506 mounts a combiner on an axis so as to flip to a stowed position on top of the projection with a motor analogous to flipping a page of a book. The rotational axis, the display surface of the combiner, and the projector are arranged at fixed angles.
U.S. Pat. No. 4,775,218 uses a LED alignment detector to determine whether a holographic combiner based with an infinity focus is arranged with a separately mounted cathode-ray tube within a prearranged operational tolerance. The combiner only stows rearward, and the sensitive holographic optics requires unique pilot calibration such that the combiner cannot be easily adjusted to a pilot's preference.
U.S. Pat. No. 5,517,337 shows a retractable holographic combiner with a movable holographic mirror placed before the pilot's eyes, and designed for presenting light images collimated at infinity, superimposed on the external scene, and coming from a projector positioned up-line with respect to the combiner. The holographic mirror is connected to a fixed part of the aircraft by a hinged support constituted by a single lateral connecting arm to the fixed part of the aircraft. However, the projector and the arm are separately fixed to the aircraft rather than integrated into one unit to be fixed to an aircraft. In addition, the arm only stows rearward. Further, the system uses holographic components which are sensitive to alignment.
U.S. Pat. No. 5,867,287 shows a HUD with a lens de-centered to the optical axis of the bright display backlighting illumination which requires a high intensity halogen bulb, IR filters, Fresnel lens and cooling fans. In addition, its display emits a yellow orange color due to the low dimming levels of the incandescent bulb such that a green display used in aircraft would turn brown at night rather than stay the same color. Furthermore, the halogen bulb reflectors result in a “Flashlight beam” effect that must be de-centered and diffused to provide even illumination. Holographic optical elements, including lenses, mirrors, gratings, prisms and beam splitters made by holographic methods, operate efficiently only over a narrow band of wavelengths.
U.S. Pat. No. 6,072,444 provides a HUD device mounting assembly that enables optical alignment between the HUD projector and the image combiner, although the combiner assembly and the optical projector are separately mounted to the cockpit of an aircraft. The components are not integrated into a single unit to reduce the likelihood of tolerance issues.
U.S. Pat. No. 6,343,863 uses a bulky frame to support and align an optical unit and a head-up display in a cockpit of an aircraft, and a sensor coupled to the frame for sensing the vertical position of the frame and providing a signal to the computer to adjust at least part of the image displayed on the combiner to correspond to the position of the frame. The frame only moves in a generally vertical direction relative to the cockpit, rather than any other directions, and it requires a motor to move the bulky frame.
U.S. Pat. No. 4,725,125 stows a projector and a combiner flatly into the dashboard of a vehicle using kinematic chains. Dash mounting (rather than head-mounting) causes significant sun intrusion issues.
U.S. Pat. No. 6,301,053 shows a combiner assembly 20 having an optical combiner 21 mounted to a housing 22, which is further arranged for mounting to a roof structure of a flight deck of an aircraft. Via the combiner, a user views an outside scene overlaid with a projected image. However, the combiner and stowage arm assembly is separately mounted to the aircraft from a display forming section (i.e., a projector; not shown). In addition, the combiner and stowage arm assembly is complex since it requires kinematic linkages with four pivot points.
In view of the state of the prior art as discussed above, there is a demand for a self-contained, universal compatible, low-cost heads-up display devices to “fit” into existing vehicles, while delivering acceptable optical and image brightness performance.